Standby liquefied petroleum gas unit



Sept. 30, 1969 v. H. BROWN STANDBY LIQUEFIED PETROLEUM GAS UNIT 2Sheets-Shegt 2 Filed June 8, 1966 INVENTOR lr/e A E Own BY WSEcr 'eJ'ZATTORNEY United States Patent 3,469,956 STANDBY LIQUEFIED PETROLEUM GASUNIT Verle H. Brown, Seattle, Wash, assignor to E. Sam Dick Co., Inc.,Seattle, Wash. Filed June 8, 1966, Ser. No. 556,229 Int. Cl. C10j 1/06US. Cl. 48-102 5 Claims ABSTRACT OF THE DISCLOSURE Standby unit providesa mixture of air and liquefied petroleum gas to be fed directly into anindustrial gas users supply line for use during periods when natural gassupply is cut off in favor of residential users. Th LP gas vaporizer inthe unit is partially enclosed within the surge tank which stores theair-gas mixture, to provide heat transfer from the vaporizer to thestored mixture and thereby maintain it in a vaporized state withoutnecessity for a separate heat source for the surge tank itself.

This invention is for a liquefied petroleum gas unit which is normallymaintained on a standby basis and which may b placed in operation in ashort time.

As is well known, an industrial user of natural gas during a shortage ofnatural gas must allow the residential user first use of availablenatural gas. If there be no available natural gas, then the industrialuser cannot use natural gas and either must cease using gas or use gasin a standby unit. For example, on a cold day residential users andindustrial users of natural gas may use more than what they normally useon a day having a temperature a few degrees higher. The capacity of thenatural gas system is not sutficient to supply both the residential userand the industrial user. Therefore, it is necessary for the industrialuser to lessen the use of natural gas or to cease using the natural gas.In order to continue to operate in such a situation an industrial userwill normally have a standby liquefied petroleum gas unit. Ordinarily,the petroleum gas is not compatible with natural gas and it is necessaryto mix the petroleum gas with air to form a petroleum gas and airgaseous mixture. When the industrial user is notified that natural gaswill no longer be available to him, the industrial user may haveapproximately three hours advance notice. Prior equipment which has beenused by industrial users in such situations has comprised a storage tankfor storing liquefied petroleum gas and also a storage tank for storingthe petroleum gas and air gaseous mixture. On cold days the petroleumgas in the petroleum gas and ai gaseous mixture has had a tendency tofreeze to form liquified petroleum gas. This has left a mixture rich inair and which mixture does not burn properly. To prevent the petroleumgas in the petroleum gas and air gaseous mixture from freezing andseparating there has been provided external heating means in the storagetank for the petroleum gas and air gaseous mixture. Such heating meanshas tended to increase the initial cost of the equipment and also hastended to increase the cost for maintaining a gaseous mixture ofpetroleum gas and air.

With this background and having worked with natural gas and petroleumgas, I have invented a standby liquefied petroleum gas unit having as anobject the provision of such a unit which can rapidly be placed in useon short notice; to provide such a unit which can be placed in use withrelatively no effort; to provide such a unit which is clean in operationand does not produce smudge in the air and does not have a strong odor;to provide such a unit which uses the same piping as natural gas; toprovide such a unit which in itself has no moving parts; to provide sucha unit which has positive action in cold weather and does not allowpetroleum gas in the petroleum gas and air gaseous mixture to freeze andseparate from the mixture; to provide such a unit which is a smallcompact unit for its capacity; to provide such a unit which can binconspicuously placed in an industrial area and, in certaincircumstances, can be substantially hidden from view; to provide such aunit which is attractive in appearance; to provide such a unit whosemounting and Support is simple in construction and easy to erect; toprovide such a unit which is a complete package in itself; to providesuch a unit which is inexpensive and which makes it possible to ship thecomplete assembled unit; to provide such a unit which is small in thevolume it occupies and yet has the same capacity as larger standbyliquefied petroleum gas units; to provide such a unit which iseconomical in a small installation; to provide such a unit which has noexternal heating means for maintaining the petroleum gas in a vaporphase in the petroleum gas and air gaseous mixture and does not requiresteam tracing or jacketing on the surge tank; to provide such unit whichcan readily produce a substantially constant ratio of air to petroleumgas in the gaseous mixture; and, to provide such unit which has a widerange of flow rate of a substantially constant ratio of air to petroleumgas in the petroleum gas and air gaseous mixture.

These and other important objects and advantages of the invention willbe brought forth upon reference to the accompanying drawings, thedetailed disclosure of the invention and the appended claims.

In the drawings:

FIGURE 1 is a side elevational view of the standby liquefied petroleumgas unit and illustrates the structure of such unit; and

FIG. 2, on an enlarged scale, is a fragmentary vertical cross-sectionalview illustrating the internal structure of the vaporizer of the standbyliquefied petroleum gas unit, without the insulation jackets shown inFIG. 1.

In FIG. 1 there is illustrated a standby liquefied petroleum gas unit10. Such a unit 10 may be considered to comprise three separate units,namely the vaporizer 12, a mixer 14, and a surge tank 16.

The surge tank 16 is illustrated in FIG. 1. The central portion of thissurge tank may b considered to comprise a circular band while the upperor top portion and the lower or bottom portion may be considered to bein the configuration of an ellipsoid. The surge tank 16 may be of thesethree separate portions and which portions are welded to form the tankproper. In the bottom it is seen that there is an adapter 18 and a tankdrain 20 having a valve.

Near one side of the surge tank 16, see FIG. 2, there is an opening 22in the lower eliptical portion and an opening 24 in the upper elipticalportion. In the openings 22 and 24 there is positioned the vaporizer 12.

The vaporizer 12 is an upright housing in the configuration of anupright circular cylinder and has a lower portion 26 and an upperportion 28. The lower portion 26 connects with a foot 29. Near thebottom of the lower portion 26 there is a plate 30 which seals off thelower portion 26. Above the plate 30 there is an opening 32 in the wall26. An adapter or fitting 34 is welded to the outside wall 26 so as toconnect with the opening 32. As is seen in FIG. 2 the lower end or plate30 is welded to the inside of the housing of 26. Above the plate 30there is welded a plate 36. In the plate 36 there are numerous openings38. The plates 30 and 36, in conjunction with the walls of the lowerportion 26, define a chamber 40. The chamber 40 may he referred to as asteam chamber.

In the wall 26 directly above the plate 36 there is an an opening 42. Apipe 44 is welded to the outside of the wall 26 and connects with thisopening 42. Further, above the plate 36 and in the wall 26 is an opening46. A pipe 48 is welded to the outside of the wall 26 and connects withthe opening 46. On the outside of the lower portion 26 there is weldedcircular flange 50. This circular flange 50 has a number of passageways52. Positioned on top of the circular flange 50 is a plate or divider 54having a number of passageways or opening 56 therein.

On the lower part or lower end of the upper section 28 there is welded aflange 58 having a number of passageways 60 therein. Tie rods 62 andnuts 64 connect together the flanges 50 and 58 so as to squeeze theplate 54 between the upper part of the lower section 26 and the lowerpart of the upper section 28. The volume defined by the plate 36, theplate 54, and the walls of the lower section 26 may be considered to bea condensation chamber 66. Onto the pipe 48 there is attached a pressuregauge 49. Steam is introduced into the steam chamber 40 through pipe 34and opening 32. The opening 42 and pipe 44 are where some of thecondensate in the condensation chamber 66 is removed.

In FIG. 2 it is seen that in the openings 38 in the plate 36 there arepositioned the lower end of pipes 70. The pipes 70 project through theopenings 56 in the plate 54 and well up into the upper section 28 of thevaporizer 12. In the openings 56 in the plate 54 there are pipes ortubes 72. The tubes 72 are of a larger internal diameter than theexternal diameter of the pipes 70. In fact, the tubes 72 may beconsidered to be circular housings for the upper part of the pipes 70.In FIG. 2 it is seen that the upper part of the tubes or housing 72 aresealed or closed. Also, in FIG. 2 it is seen that the ends of the pipes70 are open so that with the lower ends of the pipes 70 in the steamchamber 40 it is possible for the steam chamber 40 to connect withcondensation chamber 66 by means of the pipes 70 and the housing 72. Thepurpose is readily seen as steam may enter into the steam chamber 40 andflow through the pipes 70 and into the housing 72. The condensation mayflow down the interior of the housings 72 and into the condensationchamber 66.

In the lower part of the upper section 28 and in the wall of the uppersection 28 there is an opening 74. Pipe 76 is welded to the outersurface of the wall of a section 28 and in alignment with the opening74. Further, in part of the upper section 28 there is an opening 78 inthe wall and a pipe 80 is welded to the outer surface of the wall sothat the pipe 80 is in alignment with the opening 78. Slightly above theopening 78 there is an opening 82. A pipe 84 is welded to the outersurface of the wall of the section 28 and in alignment with the opening82. Above the opening 82 there is an opening 86 in the wall of section28 and a pipe 88 is welded to the outer surface of the wall with thepipe in alignment with opening 86. Finally, on top of the housing or theupper section 28 there is an opening 90.

In an installation in which there are two mixers 14 there are twoopenings 86 and two pipes 88, at approximately 180 angle with eachother.

In FIG. 1 it is seen that strainer 94 connects with a four-way cross 96.One end of the strainer 94 connects with a source of liquefied petroleumgas (not shown). The four-way cross 96 connects with a valve 98 which inturn connects with piping 100. The piping 100 connects with a normallyclosed solenoid valve 102. The valve 102 connects with piping 104. Thepiping 104 connects with a T 106. The T 106 connects with suitablepiping 108. The piping 108 connects with pipe 76 so as to introduceliquefied petroleum gas into the upper section 28 of the vaporizer 12.The T 106 also connects with piping 110. The piping 110 connects with aT 112. The T 112 by means of piping 114 connects with a one-wayback-flow check valve 116. The check valve 116 connects with piping 118and relieves excess pressure from the vaporizer back to the supply tankwhen the solenoid valve 102 is 4 closed. The T 112 also connects withthe valve 120. The valve 120 by means of piping 122 connects with thefourway cross 96 and provides a path for supply of gas to the vaporizerif the solenoid valve is not working or is being replaced. The normallyclosed solenoid valve 102 is electrically connected by a wire 126enclosed in a conduit 124 to a suitable transducer contained withinadapter 128 and pipe 80. After the system has been turned on by anelectrical signal at input switch 129, opening solenoid valve 102, thetransducer provides a signal for safety purposes to close the solenoidvalve when the liquid level in the vaporizer 12 exceeds a predeterminedamount.

The liquefied petroleum gas is introduced through the strainer 94 to thefour-way cross 96 and into the upper section 28 of the vaporizer 12through solenoid valve 102 and piping 104. As the vapor pressure in thevaporizer builds up, some of the liquid gas may be forced back into thesupply line through the open solenoid valve 102 to equalize thepressure. When more gas is required by the system upon withdrawal ofair-gas mixture from the surge tank, then more gas will enter thevaporizer as the pressure therein drops below the supply line pressure.

In the pipe 84 there is placed a gauge 130 and which gauge is a presuregauge for the liquefied petroleum gas and may read from 0 to 300 poundspressure. In FIG. 1 it is seen that on the side of the vaporizer thatthere is a gauge 132. This is the steam temperature gauge which may readtemperature from approximately 50-400 P. On the pipe 92 there is arelief valve stack 134 which constitutes a second safety device inaddition to the shutoff control by the transducer in adapter 128,operative in case the pressure becomes too great in the vaporizer.

A vapor pressure regulator 136 connects with the pipe 88. This vaporpressure regulator regulates the pressure of the vaporized petroleum gassupplied through flexible tube or pipe 138 to the normally closedsolenoid valve 140. The normally closed solenoid valve 140 by means ofpiping 142 connects with a T 144. On the T 144 is a orifice pressuregauge 146 which may read approximately 0-60 pounds per square inch inorifice pressure. The T 144 connects with a T 148. The T 148 connectswith an air inlet adapter 150 and a venturi tube 152 which togethercomprise the mixer 14. The vaporized petroleum gas in passing throughthe venturi tube 152 creates a vacuum or a decreased pressure so thatair enters the venturi tube through the air adapter 150 and mixes withthe vaporized petroleum gas to form the petroleum gas and air gaseousmixture.

In the upper portion of the surge tank 16 there is an adapter 154 whichleads into the interior of the surge tank 16. The venturi tube 152 bymeans of a pipe 156 connects with a valve 158. The valve 158 by means ofpipe 160 connects with the adapter 154. In this manner, with the openingof the valve 158, the petroleum gas and air gaseous mixture flow intothe interior of the surge tank 16. Again, it is seen that on top of thesurge tank 16 that there is an adapter 162. This adapter 162 connectswith the manual shut-off valve 164. The valve 164 by means of piping 166connects with a valve 168, which is part of a regulator 170. Theregulator 170 is an optional regulator for the petroleum gas and airgaseous mixture so as to regulate the pressure within a range ofapproximately 0-10 pounds per square inch pressure when required by lowcustomer supply line pressure. A suitable connecting means (not shown)is coupled with the outlet of valve 168 in the installation to conveythe petroleum gas and air gaseous mixture to the place of usage.

A pressure control sensor unit 171 positioned centrally in the top ofthe surge tank senses the pressure therein and operates the solenoidvalve 140 through suitable electrical connections 173 and 175. The gasvapor provided through regulator 136 is thus supplied to the mixer 14 byoperation of solenoid valve 140 when the surge tank pressure drops belowa predetermined value and is shut off when the mixture supplied to thetank causes the pressure to reach a second, higher value. The demand forthe air-gas mixture from the surge tank is determined by the pressure inthe customer supply line coupled to regulator valve 168.

On top of the surge tank 16 it is seen that a relief stack 172 may bepositioned.

In operation the following procedure is followed. When the operator hasbeen notified that natural gas is no longer available, then steam isintroduced through the pipe 34 and the opening 32 into the steam chamber40. Also, the normally closed solenoid valve 102 is opened automaticallywhen the system is switched on and liquified petroleum gas is introducedinto the upper section 28 of the vaporizer 12. The steam flows upwardlythrough the pipes 70 and into the housings 72. The liquefied petroleumgas contacts the outside of the housings 72 and heat energy istransferred from the steam inside the housings 72 to the liquefiedpetroleum gas on the outside of the housings 72. The liquefied petroleumgas is vaporized and most of the steam is condensed and flows downwardlyaround the pipes 70 into the condensation chamber 66. The vaporizedpetroleum gas flows out through the pipes 88, through the flexible pipe138, through the open solenoid valve 140 and to the T 148 and theventuri tube 152. Air flows into the venturi tube 152 and is mixed withthe vaporized petroleum gas to form the petroleum gas and air gaseousmixture which flows through the adapter 154 into the surge tank 16.Inside the surge tank 16 petroleum gas and air gaseous mixture is incontact with the upper section 28 of the vaporizer 12. The temperatureof the upper section 28 and the temperature inside the surge tank 16 maybe the same or the temperature of the upper section 28 may be somewhathigher than the temperature inside the surge tank 16. By having theupper section 28 inside the surge tank 16, the upper section 28functions as a heat exchanger for transferring heat energy from theupper section 28 to the contents inside the surge tank 16. In thismanner, the petroleum gas in the petroleum gas and air gaseous mixturewill not condense to form liquefied petroleum gas and air above theliquefied petroleum gas in the bottom of the urge tank 16. In otherwords, it is not necessary to have external heating means formaintaining the petroleum gas in a vapor form inside the surge tank 16as the upper section 28 performs this function. It is seen that thesurge tank 16 is supported by a leg 174 (actually, there is another legon the other side so that there are two legs 174 supporting surge tank16). In addition to the two legs 174 the vaporizer 12 functions as a legto support the surge tank 16. There may be an insulation jacket 176 (notshown in FIG. 2) around the lower section 26 of the vaporizer 12.Further, there may be insulation 178 around the lower part of the uppersection 28 before the vaporizer 12 goes into the interior of the surgetank 16. Further, there may be an insulation jacket 180 around the upperpart of the upper section 28 of the vaporizer 12.

The steam being introduced into the steam chamber 40 may be at atemperature of approximately 270 F. The liquefied petroleum gas is amxiture of propane and butane. Normally, the petroleum gas and airgaseous mixture comprises approximately 45% air and 55% petroleum gas byvolume and has a heating value of about 1,450 B.t.u. per cubic foot anda specific gravity of about 1.3. The temperature of the gaseous mixtureinside the surge tank 16 may vary in the range of approximately 150-250F., largely dependent upon the temperature outside the surge tank 16.The heat is transferred from the upper section 28 of the vaporizer 12 tothe contents of the surge tank 16 by radiant energy; by conduction fromthe petroleum gas and air gaseous mixture contacting the walls of theupper section 28; and, also by convection. Of utmost importance is thatfact that heat is transferred to the total gas and air gaseous mixtureinside the surge tank 16 so as to maintain the petroleum gas in avaporized state. Unit such as the unit which has been described can bedesigned having production capacities of from 6,000,000 to 64,000,000B.t.u.s per hour and more.

From the foregoing it is seen that I have provided a compact standbyliquefied petroleum gas unit which can be assembled and packaged in aplant and shipped as an assembled and packaged unit to the user.Further, the design is such that it may be placed. close to the usersplant and out in the open. Or, it may be placed behind shrubbery and thelike because of its small size and therefore can readily be hidden fromview.

Having presented my invention, what I claim is:

1. A standby liquified petroleum gas unit comprising:

(a) a surge tank;

(b) a vaporizer for vaporizing liquefied petroleum gas for storage insaid tank; and,

(c) said vaporizer being partially in said tank.

2. A standby liquefied petroleum gas unit according to claim 1 andcomprising said vaporizer being a support for said surge tank.

3. A standby liquefied petroleum gas unit according to claim 1 andcomprising:

(a) a mixer for mixing the petroleum gas and air to form a petroleum gasand air mixture;

(b) said mixer connecting with said vaporizer; and,

(c) said mixer connecting with said surge tank.

4. A standby liquefied petroleum gas unit, said unit comprising:

(a) a surge tank;

(b) a vaporizer for vaporizing liquefied petroleum gas;

(c) said vaporizer being an upright vaporizer;

.(d) said vaporizer being partially in said surge tank so as to be ableto transmit heat energy to the contents inside surge tank;

(e) said vaporizer comprising heat transfer means;

(f) said vaporizer comprising a chamber housing said heat transfermeans;

(g) an inlet to said chamber for introducing liquefied petroleum gasinto said chamber;

(h) an outlet for said chamber to allow vaporized petroleum gas to leavesaid chamber; and,

(i) said outlet connecting with said surge tank.

5. A standby liquefied petroleum gas unit according to claim 4 andcomprising:

(a) said heat transfer means comprising upright pipes for heated vapor;

(b) a mixer for mixing vaporized petroleum gas and air to form a gas andair mixture;

(c) said mixer connecting with said vaporizer;

((1) said mixer connecting with said surge tank; and,

(c) said mixer comprising an orifice for mixing the petroleum gas andair.

References Cited UNITED STATES PATENTS 2,351,131 11/1940 Kerr 62-52 XR3,285,719 ll/1966 Bodle et a1. 6251 XR 2,609,282 9/1952 Haug et a1 48196XR 1,889,162 11/1932 Thomas et a1 62-52 XR MORRIS O. WOLK, PrimaryExaminer J. D. OLSEN, Assistant Examiner U.S. C1. X.R.

